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    More Charging woes

    I recently picked up a 1978 GS750 and have put about 80 miles on the bike so far. After hearing about the common electrical issues with these bikes I tested to see if the bike was charging and at no point in the RPM range does the voltage go above 12.5. That being said the bike runs perfect and I have driven it with the lights on and almost exclusively using the starter without the battery dieing. After looking around the wiring some I found some burn marks on the yellow wire 3-way connector under the seat. The wires don't look burnt but just the insulation at the connector. My real question here is that the wiring diagram for the 8-valve 750's seems to show a voltage regulator that is separate from the rectifier. Is this correct? Also any idea why my battery hasn't died yet? What would be the next step here? Test the individual stator windings? I only have a cheapo multi-meter for now so I may have to pick up a better one. Lastly, what seems to be the best way to reduce the electrical problems. I've seen mention of replacing the regulator with a more modern style, but have found no information about this swap on the earlier bikes. Thanks in advance
    The current garage:
    1978 GS750
    1975 GT750M
    1984 CB700SC
    1982 XJ650 Seca Turbo
    1975 RD250 - 350 conversion

    #2
    If Quick test Failed then do the Stator Phases Phase B. ignore teh ohmmeter tests do all leg to leg and leg to ground at 5K RPM.

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      #3
      My bike ran for about 30 hours or so with damaged stator never going above 12.7 - still started ok, but my onboard voltmeter was not happy with me.
      your bike came stock with seperate rectifier and regulator- you should replace with a combo unit. You want to wire your stator direct to the r/r . Read those links and do testing.
      1981 gs650L

      "We are all born ignorant, but you have to work hard to stay stupid" Ben Franklin

      Comment


        #4
        I got a better multi meter and I'm going to start doing some testing today. Although I'm pretty sure its going to need the whole lot. Stator and R/R. Is there any issues with replacing my seperate R/R that I would run into or can I just run all the wires into the unit? I am currently looking into the SH-775 unit but am noticing that most of these come with a modern style multi-pin connector. Do most people buy the male ends and wire them into the harness or what?
        The current garage:
        1978 GS750
        1975 GT750M
        1984 CB700SC
        1982 XJ650 Seca Turbo
        1975 RD250 - 350 conversion

        Comment


          #5
          Originally posted by The1970's View Post
          Although I'm pretty sure its going to need the whole lot. Stator and R/R.
          Not necessarily (but still very probable). Id cut the burnt connectors out and splice the wires direct. Your dealing with corroded contacts in the connectors that create electrical resistance. That friction equates to heat aka burnt wires and connectors. Also find the ground wire from your regulator and connect that direct to the neg batt terminal. Now get some electrical contact cleaner and disconnect and spray every connector on the bike.

          Contact Mr. Duaneage if you need to go the new RR route....
          82 1100 EZ (red)

          "You co-opting words of KV only thickens the scent of your BS. A thief and a putter-on of airs most foul. " JEEPRUSTY

          Comment


            #6
            Originally posted by The1970's View Post
            I got a better multi meter and I'm going to start doing some testing today. Although I'm pretty sure its going to need the whole lot. Stator and R/R. Is there any issues with replacing my seperate R/R that I would run into or can I just run all the wires into the unit? I am currently looking into the SH-775 unit but am noticing that most of these come with a modern style multi-pin connector. Do most people buy the male ends and wire them into the harness or what?
            A lot of people but the corrector but that adds a lot to the overall size. You can make it work with or without, the main issue is whether you can get it to fit someplace that makes you happy.

            Comment


              #7
              Well I did some more testing today and luckily things seemed to work out this time. Maybe it was the new meter or maybe I just wasn't paying enough attention when I checked it the first time but the bike passed the quick test this time. The only thing worth mentioning is that when bringing the RPM to 2500 and 5000 it took maybe 30 - 45 seconds of sustained RPM before the battery came up to the specified voltage. Is this still okay? It is also on the low end of all the specs. I plan on riding it to work again and rewiring all the grounds directly to the battery and cleaning the connections. Hopefully this will be the last of the charging issues for now
              The current garage:
              1978 GS750
              1975 GT750M
              1984 CB700SC
              1982 XJ650 Seca Turbo
              1975 RD250 - 350 conversion

              Comment


                #8
                Look up single point grounding (SPG) before you re-do your grounds.
                Jordan

                1977 Suzuki GS750 (My first bike)
                2000 Kawasaki ZRX1100
                1973 BMW R75/5

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